Yet the Panthers refused to yield and set up a grandstand finish when Dallin Watene-Zelezniak took advantage of an Isaah Yeo offload in the 70th minute.
But, in front of a strong crowd of 17,821, the Eels held on to finally end their losing streak at five games.
It was a horror start for the Panthers, who were left stunned at 12-0 when they watched their star fullback go down.
First Will Hopoate's quick hands allowed Ryan Morgan to open the scoring in the fourth minute, before Semi Radradra helped the Eels go 100 metres to put Reece Robinson over in the next set.
The sight of Moylan limping off just three minutes later completed the nightmare opening.
From there the hosts spent the rest of the half fending off raid upon raid on their tryline, and on the rare occasion they got into an attacking set, Hopoate saved a certain Waqa Blake try with a one-on-one steal.
By the end of the half the Eels, who had missed their past six shots at goal, took a 14-0 lead into the break on Sandow's 29th minute penalty.
Penrith got the early try they needed in the second half when Yeo finished off a James Segeyaro break in the 50th minute.
Soward was felled by Pauli in the build-up.
Stepping into the pivot role, Cartwright continued the momentum after dummying twice and producing a neat corner pass for David Simmons three minutes later.
The Panthers youngster completed the comeback in the 58th when the Eels were caught short-handed before fighting back to score a sorely-needed victory.
- AAP
